Backpack



FIG. 1 is a perspective view of a backpack showing the claimed design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a left side elevational view thereof;

FIG. 4 is a front side elevational view thereof;

FIG. 5 is a right side elevational view thereof;

FIG. 6 is a back side elevational view thereof; and,

FIG. 7 is a bottom plan view thereof.

The broken line depicts a portion of the article that forms no part ofthe claimed design.

CLAIM The ornamental design for a backpack, as shown and described.